Without limiting the scope of the present invention, its background is described with reference to the production of hydrocarbons through a wellbore traversing unconsolidated or loosely consolidated formations, as an example.
It is well known in the subterranean well drilling and completion art that particulate materials such as sand may be produced during the production of hydrocarbons from a well traversing one or more unconsolidated or loosely consolidated subterranean formations. Numerous problems may occur as a result of the production of such particulate. For example, the particulate causes abrasive wear to components within the well, such as tubing, pumps and valves. In addition, the particulate may partially or fully clog the well creating the need for an expensive workover. Also, if the particulate matter is produced to the surface, it must be removed from the hydrocarbon fluids by processing equipment at the surface.
One method for preventing the production of such particulate material to the surface is gravel packing the well adjacent the unconsolidated or loosely consolidated production interval. In a typical gravel pack completion, a completion string including a packer, a circulation valve, a fluid loss control device and one or more sand control screens is lowered into the wellbore to a position proximate the desired production interval. A service tool is then positioned within the completion string and a fluid slurry including a liquid carrier and a particulate material known as gravel is then pumped through the circulation valve into the well annulus formed between the sand control screens and the perforated well casing or open hole production zone.
The liquid carrier either flows into the formation or returns to the surface by flowing through the sand control screens or both. In either case, the gravel is deposited around the sand control screens to form a gravel pack, which is highly permeable to the flow of hydrocarbon fluids but blocks the flow of the particulate carried in the hydrocarbon fluids. As such, gravel packs can successfully prevent the problems associated with the production of particulate materials from the formation. During certain gravel packing operations in well having multiple zones, the service tool used to deliver the gravel slurry may be positioned relative to each of the zones to be completed in a single trip. For example, the service tool is typically first positioned relative to the lowermost zone to perform the first gravel packing operation then lifted uphole to sequentially perform gravel packing operations on the next uphole zone until each of the zones is gravel packed. It has been found, however, that such axially movement of the service tool relative to the completion string lacks precision and certainty regarding the exact location of certain service tool components relative to particular landing points within the completion string. Specifically, the service tool is repositioned by raising and lowering the block at the surface, which is typically thousands of feet away from the downhole landing points of the service tool. The distance the block is moved at the surface, however, does not directly translated to the distance the service tool moves downhole. For example, movement of the service tool is effected by both static and dynamic frictional forces, gravitational forces, pressure forces and the like. This is particularly acute in slanted, deviated and horizontal wells. In addition, the length of the service tool string is not constant due to thermal effects, particularly in deep-water completions.
Therefore, a need has arisen for systems and methods for completing a wellbore that traverses one or more subterranean hydrocarbon bearing formations that enhance the precision and certainty regarding the location of the service tool relative to a particular landing point or landing points within the completion string. A need has also arisen for such systems and methods that are able to correlate between the distance the block is moved at the surface and the distance the service tool moves downhole. Further, need has arisen for such systems and methods that are able to account for the thermal effects experienced by the service tool string in downhole environments including subsea environments.